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About Hafnium

Hafnium Bohr

In 1869, Dmitri Mendeleev’s periodic table predicted the existence of an element with 72 protons that would be chemically similar to zirconium . Though Henry Moseley and Niels Bohr’s subsequent theoretical models of the elements supported this prediction, it was not until 1923 that Georg von Hevesy and Dirk Coster provided the first empirical evidence of the elusive element 72, the penultimate element with stable isotopes to be discovered (followed by rhenium two years later). While working at the Bohr Institute of Theoretical Physics in Copenhagen, the two chemists identified the new element via x-ray spectroscopy analysis of a zirconium ore and named it "hafnium" after Hafnia, the Latin name for Copenhagen.

True to Mendeleev’s theory, Hafnium is extremely similar to zirconium; with nearly identical atomic radii, the two always occur together in nature in a continuous solid-solution and are two of the most difficult elements to separate. Primarily zirconium-based minerals typically contain 1-3% hafnium, the most common (and the subject of Coster and von Hevesy’s experiment) being zircon (zirconium silicate) with up to 4% hafnium by content. Other such zirconium-rich minerals include eudialyte, thortveitite, cyrtolite, armstrongite, alvite, and hafnon; the two elements can also be found in minerals such as the titanium ores ilmenite and rutile. Hafnium metal is primarily obtained as a byproduct of producing high-purity nuclear grade zirconium metal. The metals are typically chemically separated via a liquid-liquid extraction process that utilizing the slightly different solubilities of the two metals’ salts.

In its elemental form, hafnium is a ductile gray metal with a brilliantly lustrous silver sheen. Exposure to air causes the metal to form an impenetrable oxide film on its surface which lends the metal an extremely high resistance to corrosion and attack by most acids and alkalis. Because Hafnium’s melting point is high among its fellow transition metals, it is occasionally classified as a refractory metal. Like many other metals, hafnium as a fine powder is pyrophoric, meaning that it can ignite in air; for this reason, it is considered a hazardous material despite being non-toxic to humans. Thought hafnium shares many chemical and physical properties with zirconium, the two metals differ significantly in their densities (hafnium being roughly twice as dense) and their nuclear properties. Hafnium is an excellent neutron absorber with a high thermal neutron cross section, about 600 times that of zirconium, and one of its primary commercial uses is in control rods of nuclear reactors. It has also been used to enhance radiotherapy in the treatment of cancer.

Compound and alloy forms of hafnium are notable for their refractory properties. The melting points of several hafnium compounds are unparalleled within their respective groups: hafnium nitride’s (3310 °C) is the highest of any nitride, hafnium carbide’s (3890 °C) is the highest of any known binary compound, and tantalum hafnium carbide’s (4215 °C) is the single highest of any known compound. Thus, forms of hafnium are frequently employed in high-temperature environments as components of furnace linings, ceramics, rocket thrusters and jet engines for the aerospace industry, nozzle tips for plasma arc cutting, and wear resistant coatings. High performance superalloys typically contain hafnium in combination with metals like titanium, tungsten, and niobium; the metal improves creep ductility, strengthens grain boundaries, and increases corrosion resistance. Other applications for hafnium include serving as an oxygen and nitrogen “getter” in vacuum tubes and incandescent lighting, in geological dating (as isotopes), and in organic catalysis. Additionally, compounds like hafnium oxide and hafnium silicate have shown great promise as high-k dielectric materials that increase efficiency of semiconductor devices such as integrated circuits and transistors in the field of advanced microelectronics.


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There are relatively few technical uses for hafnium and, due to its ability as a nuclear "getter" or absorber of neutrons, much of the hafnium that is produced is used in control rods for nuclear reactors. Hafnium is also used in iron, titanium, niobium, tantalum, and other alloys. Hafnium is replacing polysilicon as the principle gate or electrode material in metal-oxide semiconductor field effect transistors (MOSFETs), which are the basis for all modern semiconductors. As semiconductors get smaller, the limiting factor in further size reduction has been the ability of the silicon dioxide gate to perform below 10 angstroms where leakage occurs. High Purity (99.999%) Hafnium (Hf) Sputtering TargetRecent research has been devoted to the development of high-k materials which can function as a di-electric barrier or gate with lower leakage. Using hafnium based alloys as this di-electric gate has allowed for the development of MOSFET gates smaller than 10 angstroms. This allows for further size reduction, reduced switching power requirements and improved performance. High Purity (99.999%) Hafnium Oxide (HfO2) PowderHafnium is available as metal and compounds with purities from 99% to 99.999% (ACS grade to ultra-high purity). Elemental or metallic forms of hafnium include pellets, rod, wire and granules for evaporation source material purposes. Hafnium nanomaterials provide ultra-high surface area which nanotechnology research and recent experiments demonstrate function to create new and unique properties and benefits. Hafnium oxide is available in powder and dense pellet form for such uses as optical coating and thin film applications. Oxides tend to be insoluble. Fluorides are another insoluble form for uses in which oxygen is undesirable such as metallurgy, chemical and physical vapor deposition and in some optical coatings. Hafnium is also available in soluble forms including chloride, nitrate and acetate. These compounds can be manufactured as solutions at specified stoichiometries.

Hafnium Properties

Hafnium(Hf) atomic and molecular weight, atomic number and elemental symbol Hafnium is a Block D, Group 4, Period 6 element. The number of electrons in each of Hafnium's shells is 2, 8, 18, 32, 10, 2 and its electronic configuration is [Xe] 4f14 5d2 6s2. Hafnium Bohr ModelIn its elemental form, CAS 7440-58-6, hafnium has a steel gray appearance. Hafnium does not exist as a free element in nature. It is found in zirconium compounds such as zircon (ZrSiO4). Hafnium was first predicted by Dmitri Mendeleev in 1869 but it was not until 1922 that it was first isolated Dirk Coster and George de Hevesy.

Symbol: Hf
Atomic Number: 72
Atomic Weight: 178.49
Element Category: transition metal
Group, Period, Block: 4, 6, d
Color: silvery/ gray steel
Other Names: Afnio, Háfnio, Hafnio
Melting Point: 2233 °C, 4051 °F, 2506 K
Boiling Point: 4603 °C,8317 °F, 4876 K
Density: 13.31 kg·cm3
Liquid Density @ Melting Point: 12 g·cm3
Density @ 20°C: 13.2 g/cm3
Density of Solid: 13310 kg·m3
Specific Heat: 0.14 (kJ/kg K)
Superconductivity Temperature: 0.128 [or -273.022 °C (-459.44 °F)] K
Triple Point: N/A
Critical Point: N/A
Heat of Fusion (kJ·mol-1): 25.5
Heat of Vaporization (kJ·mol-1): 570.7
Heat of Atomization (kJ·mol-1): 618.9
Thermal Conductivity: 23.0 W·m-1·K-1
Thermal Expansion: (25 °C) 5.9 µm·m-1·K-1
Electrical Resistivity: (20 °C) 331 nΩ·m
Tensile Strength: N/A
Molar Heat Capacity: 25.73 J·mol-1·K-1
Young's Modulus: 78 GPa
Shear Modulus: 30 GPa
Bulk Modulus: 110 GPa
Poisson Ratio: 0.37
Mohs Hardness: 5.5
Vickers Hardness: 1760 MPa
Brinell Hardness: 1700 MPa
Speed of Sound: (20 °C) 3010 m·s-1
Pauling Electronegativity: 1.3
Sanderson Electronegativity: N/A
Allred Rochow Electronegativity: 1.23
Mulliken-Jaffe Electronegativity: N/A
Allen Electronegativity: N/A
Pauling Electropositivity: 2.7
Reflectivity (%): N/A
Refractive Index: N/A
Electrons: 72
Protons: 72
Neutrons: 106
Electron Configuration: [Xe] 4f14 5d2 6s2
Atomic Radius: 159 pm
Atomic Radius,
non-bonded (Å):
Covalent Radius: 175±10 pm
Covalent Radius (Å): 1.64
Van der Waals Radius: 200 pm
Oxidation States: 4, 3, 2 (amphoteric oxide)
Phase: Solid
Crystal Structure: Hexagonal
Magnetic Ordering: paramagnetic
Electron Affinity (kJ·mol-1) 1.64
1st Ionization Energy: 658.52 kJ·mol-1
2nd Ionization Energy: 1437.64 kJ·mol-1
3rd Ionization Energy: 2248.12 kJ·mol-1
CAS Number: 7440-58-6
EC Number: 231-166-4
MDL Number: MFCD00011032
Beilstein Number: N/A
SMILES Identifier: [Hf]
InChI Identifier: InChI=1S/Hf
PubChem CID: 23986
ChemSpider ID: 22422
Earth - Total: 230 ppb
Mercury - Total: 177 ppb
Venus - Total: 241 ppb
Earth - Seawater (Oceans), ppb by weight: 0.008
Earth - Seawater (Oceans), ppb by atoms: 0.00028
Earth -  Crust (Crustal Rocks), ppb by weight: 3300
Earth -  Crust (Crustal Rocks), ppb by atoms: 380
Sun - Total, ppb by weight: 1
Sun - Total, ppb by atoms: 0.01
Stream, ppb by weight: N/A
Stream, ppb by atoms: N/A
Meterorite (Carbonaceous), ppb by weight: 170
Meterorite (Carbonaceous), ppb by atoms: 20
Typical Human Body, ppb by weight: N/A
Typical Human Body, ppb by atom: N/A
Universe, ppb by weight: 0.7
Universe, ppb by atom: 0.005
Discovered By: Dirk Coster and George de Hevesy
Discovery Date: 1922
First Isolation: Dirk Coster and George de Hevesy (1922)

Health, Safety & Transportation Information for Hafnium

Hafnium is not toxic; however, safety data for hafnium and its compounds can vary widely depending on the form. For potential hazard information, toxicity, and road, sea and air transportation limitations, such as DOT Hazard Class, DOT Number, EU Number, NFPA Health rating and RTECS Class, please see the specific material or compound referenced in the Products tab. The below information applies to elemental (metallic) Magnesium.

Safety Data
Material Safety Data Sheet MSDS
Signal Word Danger
Hazard Statements H228
Hazard Codes F
Risk Codes 11
Safety Precautions N/A
RTECS Number MG4600000
Transport Information N/A
WGK Germany nwg
Globally Harmonized System of
Classification and Labelling (GHS)
Review and Print SDS for Hafnium Metal


Date Created: 05/15/2015
Date Revised: 05/15/2015


Product Name: Hafnium Metal

Product Number: All applicable American Elements product codes, e.g. HF-M-02, HF-M-025, HF-M-03, HF-M-035, HF-M-04, HF-M-05

CAS #: 7440-58-6

Relevant identified uses of the substance: Scientific research and development

Supplier details:
American Elements
1093 Broxton Ave. Suite 2000
Los Angeles, CA 90024
Tel: +1 310-208-0551
Fax: +1 310-208-0351

Emergency telephone number:
Domestic, North America +1 800-424-9300
International +1 703-527-3887


Classification of the substance or mixture
Classification according to Regulation (EC) No 1272/2008
The product is not classified as hazardous to health or the environment according to the CLP regulation.
Classification according to Directive 67/548/EEC or Directive 1999/45/EC
Not applicable
Information concerning particular hazards for human and environment:
The product does not have to be labelled due to the calculation procedure of the "General Classification guideline for preparations of the EU" in the latest valid version.
Hazards not otherwise classified
No information known.
Label elements
Labelling according to Regulation (EC) No 1272/2008
Not applicable
Hazard pictograms
Not applicable
Signal word
Not applicable
Hazard statements
Not applicable
WHMIS classification
Not controlled
Classification system
HMIS ratings (scale 0-4)
(Hazardous Materials Identification System)

Health (acute effects) = 0
Flammability = 0
Physical Hazard = 0
Other hazards
Results of PBT and vPvB assessment
PBT: Not applicable.
vPvB: Not applicable


Chemical characterization: Mixtures
Dangerous components: Not applicable
Additional information: None known.
Non-Hazardous Ingredients
7440-58-6 Hafnium 98.0%
7440-67-7 Zirconium 2.0%


Description of first aid measures
General information
No special measures required.
After inhalation
Seek medical treatment in case of complaints.
After skin contact
Generally the product does not irritate the skin.
After eye contact
Rinse opened eye for several minutes under running water. If symptoms persist, consult a doctor.
After swallowing
If symptoms persist consult doctor.
Information for doctor
Most important symptoms and effects, both acute and delayed
No further relevant information available.
Indication of any immediate medical attention and special treatment needed
No further relevant information available.


Extinguishing media
Suitable extinguishing agents
Special powder for metal fires. Do not use water.
For safety reasons unsuitable extinguishing agents
Carbon dioxide
Special hazards arising from the substance or mixture
If this product is involved in a fire, the following can be released:
Metal oxide fume
Advice for firefighters
Protective equipment: No special measures required.


Personal precautions, protective equipment and emergency procedures
Not required.
Environmental precautions:
Do not allow material to be released to the environment without proper governmental permits.
Do not allow product to reach sewage system or any water course.
Do not allow to penetrate the ground/soil.
Methods and material for containment and cleaning up:
Pick up mechanically.
Prevention of secondary hazards:
No special measures required.
Reference to other sections
See Section 7 for information on safe handling
See Section 8 for information on personal protection equipment.
See Section 13 for disposal information.


Precautions for safe handling
Keep container tightly sealed.
Store in cool, dry place in tightly closed containers.
Information about protection against explosions and fires:
No special measures required.
Conditions for safe storage, including any incompatibilities
Requirements to be met by storerooms and receptacles:
No special requirements.
Information about storage in one common storage facility:
Store away from halogens.
Store away from halocarbons.
Further information about storage conditions:
Keep container tightly sealed.
Store in cool, dry conditions in well sealed containers.
Specific end use(s)
No further relevant information available.


Additional information about design of technical systems:
No further data; see section 7.
Control parameters
Components with limit values that require monitoring at the workplace:
7440-58-6 Hafnium (98.0%)
PEL (USA) Long-term value: 0.5 mg/m³ as Hf
REL (USA) Long-term value: 0.5 mg/m³ as Hf
TLV (USA) Long-term value: 0.5 mg/m³ as Hf
EL (Canada) Long-term value: 0.5 mg/m³ as Hf
EV (Canada) Long-term value: 0.5 mg/m³
7440-67-7 Zirconium (2.0%)
PEL (USA) Long-term value: 5 mg/m³ as Zr
REL (USA) Short-term value: 10 mg/m³
Long-term value: 5 mg/m³ as Zr
TLV (USA) Short-term value: 10 mg/m³
Long-term value: 5 mg/m³ as Zr
EL (Canada) Short-term value: 10 mg/m³
Long-term value: 5 mg/m³ as Zr
EV (Canada) Short-term value: 10 mg/m³
Long-term value: 5 mg/m³ as zirconium
Additional information: No data
Exposure controls
Personal protective equipment
General protective and hygienic measures
The usual precautionary measures for handling chemicals should be followed.
Maintain an ergonomically appropriate working environment.
Breathing equipment: Not required.
Protection of hands: Not required.
Penetration time of glove material (in minutes)
Not determined
Eye protection: Safety glasses
Body protection: Protective work clothing.


Information on basic physical and chemical properties
General Information
Form: Solid in various forms
Color: Grey to silver
Odor: Odorless
Odor threshold: Not determined.
pH-value: Not applicable.
Change in condition
Melting point/Melting range: 2227 °C (4041 °F)
Boiling point/Boiling range: 4603 °C (8317 °F)
Sublimation temperature / start: Not determined
Flammability (solid, gaseous): Not determined.
Ignition temperature: Not determined
Decomposition temperature: Not determined
Auto igniting: Product is not selfigniting.
Danger of explosion: Not determined.
Explosion limits:
Lower: Not determined
Upper: Not determined
Vapor pressure at 20 °C (68 °F): 0 hPa
Density at 20 °C (68 °F): 13.31 g/cm³ (111.072 lbs/gal)
Relative density: Not determined.
Vapor density: Not applicable.
Evaporation rate: Not applicable.
Solubility in / Miscibility with Water: Insoluble
Partition coefficient (n-octanol/water): Not determined.
dynamic: Not applicable.
kinematic: Not applicable.
Solvent content:
Organic solvents: 0.0 %
Solids content: 100.0 %
Other information
No further relevant information available.


No information known.
Chemical stability
Stable under recommended storage conditions.
Thermal decomposition / conditions to be avoided:
Decomposition will not occur if used and stored according to specifications.
Possibility of hazardous reactions
No dangerous reactions known
Conditions to avoid
No further relevant information available.
Incompatible materials:
Hazardous decomposition products:
Metal oxide fume


nformation on toxicological effects
Acute toxicity: No effects known.
LD/LC50 values that are relevant for classification: No data
Skin irritation or corrosion: Generally the product does not irritate the skin.
Eye irritation or corrosion: No irritant effect.
Sensitization: No sensitizing effects known.
Germ cell mutagenicity: No effects known.
Carcinogenicity: No classification data on carcinogenic properties of this material is available from the EPA, IARC, NTP, OSHA or ACGIH.
Reproductive toxicity: No effects known.
Specific target organ system toxicity - repeated exposure: No effects known.
Specific target organ system toxicity - single exposure: No effects known.
Aspiration hazard: No effects known.
Subacute to chronic toxicity: No effects known.
Additional toxicological information:
To the best of our knowledge the acute and chronic toxicity of this substance is not fully known.
The product is not subject to classification according to internally approved calculation methods for preparations


Aquatic toxicity:
No further relevant information available.
Persistence and degradability
No further relevant information available.
Bioaccumulative potential
No further relevant information available.
Mobility in soil
No further relevant information available.
Additional ecological information:
General notes:
Do not allow material to be released to the environment without proper governmental permits.
Do not allow undiluted product or large quantities to reach ground water, water course or sewage system.
Avoid transfer into the environment.
Results of PBT and vPvB assessment
PBT: Not applicable.
vPvB: Not applicable.
Other adverse effects
No further relevant information available.


Waste treatment methods
Consult state, local or national regulations to ensure proper disposal.
Uncleaned packagings:
Disposal must be made according to official regulations.


Not applicable
UN proper shipping name
Not applicable
Transport hazard class(es)
Not applicable
Packing group
Not applicable
Environmental hazards:
Marine pollutant (IMDG):
Special precautions for user
Not applicable.
Transport in bulk according to Annex II of MARPOL73/78 and the IBC Code
Not applicable.
Transport/Additional information:
Marine Pollutant (DOT):
UN "Model Regulation":


Safety, health and environmental regulations/legislation specific for the substance or mixture
National regulations
All components of this product are listed in the U.S. Environmental Protection Agency Toxic Substances Control Act Chemical substance Inventory.
All components of this product are listed on the Canadian Domestic Substances List (DSL).
SARA Section 313 (specific toxic chemical listings)
None of the ingredients are listed.
California Proposition 65
Prop 65 - Chemicals known to cause cancer
None of the ingredients are listed.
Prop 65 - Developmental toxicity
None of the ingredients are listed.
Prop 65 - Developmental toxicity, female
None of the ingredients are listed.
Prop 65 - Developmental toxicity, male
None of the ingredients are listed.
Information about limitation of use:
For use only by technically qualified individuals.
Other regulations, limitations and prohibitive regulations
Substance of Very High Concern (SVHC) according to the REACH Regulations (EC) No. 1907/2006.
None of the ingredients are listed.
The conditions of restrictions according to Article 67 and Annex XVII of the Regulation (EC) No 1907/2006 (REACH) for the manufacturing, placing on themarket and use must be observed.
None of the ingredients is listed.
Annex XIV of the REACH Regulations (requiring Authorisation for use)
None of the ingredients is listed.
REACH - Pre-registered substances
All ingredients are listed.
Chemical safety assessment:
A Chemical Safety Assessment has not been carried out.


Safety Data Sheet according to Regulation (EC) No. 1907/2006 (REACH). The above information is believed to be correct but does not purport to be all inclusive and shall be used only as a guide. The information in this document is based on the present state of our knowledge and is applicable to the product with regard to appropriate safety precautions. It does not represent any guarantee of the properties of the product. American Elements shall not be held liable for any damage resulting from handling or from contact with the above product. See reverse side of invoice or packing slip for additional terms and conditions of sale. COPYRIGHT 1997-2016 AMERICAN ELEMENTS. LICENSED GRANTED TO MAKE UNLIMITED PAPER COPIES FOR INTERNAL USE ONLY.

Hafnium Isotopes

Naturally occurring hafnium (Hf) has five stable isotopes: 176Hf, 177Hf, 178Hf, 179Hf, and 180Hf.

Nuclide Isotopic Mass Half-Life Mode of Decay Nuclear Spin Magnetic Moment Binding Energy (MeV) Natural Abundance
(% by atom)
153Hf 152.97069(54)# 400# ms [>200 ns] Unknown 1/2+# N/A 1183.2 -
154Hf 153.96486(54)# 2(1) s ß+ to 154Lu; a to 150Yb 0+ N/A 1200.6 -
155Hf 154.96339(43)# 890(120) ms ß+ to 155Lu; a to 151Yb 7/2-# N/A 1208.68 -
156Hf 155.95936(22) 23(1) ms a to 152Yb; ß+ to 156Lu 0+ N/A 1226.07 -
157Hf 156.95840(21)# 115(1) ms a to 153Yb; ß+ to 157Lu 7/2- N/A 1234.15 -
158Hf 157.954799(19) 2.84(7) s ß+ to 158Lu; a to 154Yb 0+ N/A 1242.23 -
159Hf 158.953995(18) 5.20(10) s ß+ to 159Lu; a to 155Yb 7/2-# N/A 1250.31 -
160Hf 159.950684(12) 13.6(2) s ß+ to 160Lu; a to 156Yb 0+ N/A 1258.39 -
161Hf 160.950275(24) 18.2(5) s ß+ to 161Lu; a to 157Yb 3/2-# N/A 1266.46 -
162Hf 161.94721(1) 39.4(9) s ß+ to 162Lu; a to 158Yb 0+ N/A 1283.86 -
163Hf 162.94709(3) 40.0(6) s ß+ to 163Lu; a to 159Yb 3/2-# N/A 1291.94 -
164Hf 163.944367(22) 111(8) s ß+ to 164Lu 0+ N/A 1300.02 -
165Hf 164.94457(3) 76(4) s ß+ to 165Lu (5/2-) N/A 1308.1 -
166Hf 165.94218(3) 6.77(30) min ß+ to 166Lu 0+ N/A 1316.17 -
167Hf 166.94260(3) 2.05(5) min ß+ to 167Lu (5/2)- N/A 1324.25 -
168Hf 167.94057(3) 25.95(20) min ß+ to 168Lu 0+ N/A 1332.33 -
169Hf 168.94126(3) 3.24(4) min ß+ to 169Lu (5/2)- N/A 1340.41 -
170Hf 169.93961(3) 16.01(13) h EC to 170Lu 0+ N/A 1357.81 -
171Hf 170.94049(3) 12.1(4) h ß+ to 170Lu 7/2(+) N/A 1356.57 -
172Hf 171.939448(26) 1.87(3) y EC to 172Lu 0+ N/A 1373.96 -
173Hf 172.94051(3) 23.6(1) h EC to 173Lu 1/2- N/A 1372.73 -
174Hf 173.940046(3) 2.0(4)E+15 y a to 170Yb 0+ N/A 1380.8 0.16
175Hf 174.941509(3) 70(2) d EC to 175Lu 5/2- 0.54 1388.88 -
176Hf 175.9414086(24) Observationally Stable - 0+ N/A 1396.96 5.26
177Hf 176.9432207(23) Observationally Stable - 7/2- 0.7936 1405.04 18.6
178Hf 177.9436988(23) Observationally Stable - 0+ N/A 1413.12 27.28
179Hf 178.9458161(23) Observationally Stable - 9/2+ -0.6409 1421.2 13.62
180Hf 179.9465500(23) Observationally Stable - 0+ N/A 1429.28 35.08
181Hf 180.9491012(23) 42.39(6) d ß- to 181Ta 1/2- N/A 1437.36 -
182Hf 181.950554(7) 8.90(9)E+6 y ß- to 182Ta 0+ N/A 1436.12 -
183Hf 182.95353(3) 1.067(17) h ß- to 183Ta (3/2-) N/A 1444.2 -
184Hf 183.95545(4) 4.12(5) h ß- to 184Ta 0+ N/A 1452.28 -
185Hf 184.95882(21)# 3.5(6) min ß- to 185Ta 3/2-# N/A 1460.35 -
186Hf 185.96089(32)# 2.6(12) min ß- to 186Ta 0+ N/A 1459.12 -
187Hf 186.96459(43)# 30# s [>300 ns] Unknown N/A N/A 1467.19 -
188Hf 187.96685(54)# 20# s [>300 ns] Unknown 0+ N/A 1475.27 -