硼化镧 | 12008-21-8

• 物质功能分类: 无机化工 - 无机盐 - 硼化物、硼酸盐和过硼酸盐
• 分子结构分类: 无机化合物 - 混合金属/非金属化合物 - 类金属盐
• 中文名称: 硼化镧
• 中文别名: 六硼化镧
• CAS: 12008-21-8
• 化学式: B6La
• 分子量: 203.8
• InChiKey: OHYJFHAQNDIDQW-UHFFFAOYSA-N

物化性质

• 熔点：
  2210 °C
• 密度：
  2.61 g/cm3 at 25 °C (lit.)
• 稳定性/保质期：

  遵照规格使用和储存，则不会分解。立方晶系，CaB6型结构，空间群Pm3m，a＝4.1561 Å (4.1571 Å，即0.1 nm，下同)。

计算性质

• 辛醇/水分配系数(LogP)：
  -2.28
• 重原子数：
  7
• 可旋转键数：
  0
• 环数：
  0.0
• sp3杂化的碳原子比例：
  0.0
• 拓扑面积：
  0
• 氢给体数：
  0
• 氢受体数：
  0

安全信息

• TSCA：
  Yes
• WGK Germany：
  3

SDS

Name:	Lanthanum hexaboride 99% Material Safety Data Sheet
Synonym:	Lanthanum borid
CAS:	12008-21-8

Section 1 - Chemical Product MSDS Name:Lanthanum hexaboride 99% Material Safety Data Sheet
Synonym:Lanthanum borid

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Section 2 - COMPOSITION, INFORMATION ON INGREDIENTS

CAS#	Chemical Name	content	EINECS#
12008-21-8	Lanthanum hexaboride, 99%	99%	234-531-6

Hazard Symbols: None Listed.
Risk Phrases: None Listed.

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Section 3 - HAZARDS IDENTIFICATION
EMERGENCY OVERVIEW
The toxicological properties of this material have not been fully investigated.
Potential Health Effects
Eye:
May cause eye irritation.
Skin:
May cause skin irritation.
Ingestion:
May cause irritation of the digestive tract. The toxicological properties of this substance have not been fully investigated.
Inhalation:
May cause respiratory tract irritation. The toxicological properties of this substance have not been fully investigated.
Chronic:
No information found.

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Section 4 - FIRST AID MEASURES
Eyes: Flush eyes with plenty of water for at least 15 minutes, occasionally lifting the upper and lower eyelids. Get medical aid immediately.
Skin:
Get medical aid. Flush skin with plenty of water for at least 15 minutes while removing contaminated clothing and shoes.
Ingestion:
If victim is conscious and alert, give 2-4 cupfuls of milk or water.
Get medical aid immediately.
Inhalation:
Get medical aid immediately. Remove from exposure and move to fresh air immediately. If not breathing, give artificial respiration. If breathing is difficult, give oxygen.
Notes to Physician:

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Section 5 - FIRE FIGHTING MEASURES
General Information:
As in any fire, wear a self-contained breathing apparatus in pressure-demand, MSHA/NIOSH (approved or equivalent), and full protective gear.
Extinguishing Media:
Use water spray, dry chemical, carbon dioxide, or chemical foam.

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Section 6 - ACCIDENTAL RELEASE MEASURES
General Information: Use proper personal protective equipment as indicated in Section 8.
Spills/Leaks:
Vacuum or sweep up material and place into a suitable disposal container.

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Section 7 - HANDLING and STORAGE
Handling:
Wash thoroughly after handling. Use with adequate ventilation. Avoid contact with skin and eyes. Avoid ingestion and inhalation.
Storage:
Store in a cool, dry place. Store in a tightly closed container.

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Section 8 - EXPOSURE CONTROLS, PERSONAL PROTECTION
Engineering Controls:
Facilities storing or utilizing this material should be equipped with an eyewash facility and a safety shower. Use process enclosure, local exhaust ventilation, or other engineering controls to control airborne levels.
Exposure Limits CAS# 12008-21-8: Personal Protective Equipment Eyes: Wear appropriate protective eyeglasses or chemical safety goggles as described by OSHA's eye and face protection regulations in 29 CFR 1910.133 or European Standard EN166.
Skin:
Wear appropriate protective gloves to prevent skin exposure.
Clothing:
Wear appropriate protective clothing to prevent skin exposure.
Respirators:
Follow the OSHA respirator regulations found in 29 CFR 1910.134 or European Standard EN 149. Use a NIOSH/MSHA or European Standard EN 149 approved respirator if exposure limits are exceeded or if irritation or other symptoms are experienced.

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Section 9 - PHYSICAL AND CHEMICAL PROPERTIES

Physical State: Solid
Color: not available
Odor: Not available.
pH: Not available.
Vapor Pressure: Not available.
Viscosity: Not available.
Boiling Point: Not available.
Freezing/Melting Point: 2210 deg C
Autoignition Temperature: Not available.
Flash Point: Not available.
Explosion Limits, lower: Not available.
Explosion Limits, upper: Not available.
Decomposition Temperature:
Solubility in water: insoluble
Specific Gravity/Density: 2.6100g/cm3
Molecular Formula: B6La
Molecular Weight: 203.78

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Section 10 - STABILITY AND REACTIVITY
Chemical Stability:
Stable under normal temperatures and pressures.
Conditions to Avoid:
None reported.
Incompatibilities with Other Materials:
Strong oxidizing agents.
Hazardous Decomposition Products:
None.
Hazardous Polymerization: Has not been reported.

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Section 11 - TOXICOLOGICAL INFORMATION
RTECS#:
CAS# 12008-21-8 unlisted.
LD50/LC50:
Not available.
Carcinogenicity:
Lanthanum hexaboride, 99% - Not listed by ACGIH, IARC, or NTP.

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Section 12 - ECOLOGICAL INFORMATION

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Section 13 - DISPOSAL CONSIDERATIONS
Dispose of in a manner consistent with federal, state, and local regulations.

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Section 14 - TRANSPORT INFORMATION

IATA
Not regulated as a hazardous material.
IMO
Not regulated as a hazardous material.
RID/ADR
Not regulated as a hazardous material.

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Section 15 - REGULATORY INFORMATION

European/International Regulations
European Labeling in Accordance with EC Directives
Hazard Symbols: Not available.
Risk Phrases:
Safety Phrases:
S 24/25 Avoid contact with skin and eyes.
WGK (Water Danger/Protection)
CAS# 12008-21-8: No information available.
Canada
CAS# 12008-21-8 is listed on Canada's DSL List.
CAS# 12008-21-8 is not listed on Canada's Ingredient Disclosure List.
US FEDERAL
TSCA
CAS# 12008-21-8 is listed on the TSCA inventory.

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SECTION 16 - ADDITIONAL INFORMATION
N/A

制备方法与用途

概述

六硼化镧是一种由稀土元素镧与非金属元素硼形成的稀土硼化物，分子式为LaB₆。其密度为4.7 g/cm³，质硬而脆。从化学成分上看，它属于无机非金属材料；从材料特性上来看，它是无氧类金属难熔化合物；在用途上，则是一种信息材料。

常温下，六硼化镧产品有三种形态：粉末状、多晶体和单晶体，各有不同的应用价值。

简介

六硼化镧（lanthanum hexaboride, LaB₆）的晶体结构为CsCl结构，属于简单立方晶系。它一般呈紫色，由于La:B比例不同而可能呈现黑色或青色等颜色。LaB₆具有许多优越性能，包括电子发射强度、抗辐射性、高温化学稳定性等，因此在军事领域以及众多高科技领域有广泛的应用，如雷达、航空航天、电子工业、仪器仪表、医疗器械、家电和冶金等行业。

在制作大功率电子管、磁控管、电子束、离子束、加速器阴极等器件时，单晶六硼化镧是首选的材料。其晶体结构模型如图1所示，与其他稀土元素六硼化物一样，LaB₆属于立方晶系CsCl型，由较大的镧原子构成简单立方体，较小的硼原子则在晶格中形成八面体。

合成方法

现在六硼化镧的制备通常采用碳化硼热还原法制备。其反应式为：La₂O₃ + 3B₄C → 2LaB₆ + 3CO；由于该反应引入了碳化硼作为反应原料，产品中碳含量难以控制，且因碳化硼硬度高、粒度大，容易产生混料不均匀现象，使产品化学成分发生偏离。

另一种方法是元素合成法，采用高纯硼粉和金属镧作为原料，得到高纯产品。此方法合成的纯度较高，工艺易控，但两种原料价格昂贵，使其成本很高。

自蔓延高温合成法使用镁粉、氧化镧、三氧化二硼作为原料。这是所有方法中唯一不需要使用高温设备的方法，能源成本较低，但缺点是后处理工序较繁琐，产品纯度稍低，但在粒度方面有优势。

卤化物硼热还原法则使用氯化镧和硼粉为反应原料，得到产物单一且易于处理，可以相对容易地获得较高的纯度。高纯六硼化镧的成功研制可以为我国应用高纯硼化物的领域提供高质量稳定的产品，减少对外产品的依赖。该工艺在生产过程中受限于硼粉价格昂贵，但在一定程度上优于现有合成工艺。

发电性能

LaB₆具有较低的逸出功，是一种优秀的阴极材料，特别适用于高温、大电流密度的器件。基于其独特结构，使其具有良好的电子活性，在加热时晶胞中扩散出来的金属镧原子可以立即补充表面蒸发掉的金属镧原子，使LaB₆表面始终保持良好的阴极活性。由于LaB₆的高电导率、良好的热稳定性及化学稳定性、低逸出功和优异的阴极表面活性等特点，使其在阴极发射中得到广泛应用，成为理想的热阴极材料。

应用

六硼化镧纳米粉末在近红外波段具有吸收和散射作用，可用于制作透明隔热玻璃。LaB₆SiO₂/Fe₃O₄复合纳米颗粒综合了不同纳米颗粒的性能，具有顺磁性和近红外光热转换特性，适用于捕捉大肠杆菌与金黄色酿脓葡萄球菌；酸催化下制备的LaB₆纳米颗粒均匀分散在SiO₂薄膜中，具有近红外吸收特性，在传感器、微电子机械和光学薄膜等领域中有广泛应用。

参考文献

1. 仪修超. 六硼化镧纳米粉末制备技术的研究[D]. 电子科技大学,2015.
2. 姜岩, 王颖. 硼热还原法制备六硼化镧粉末[J]. 辽宁化工,2010,39(09):904-905+908.
3. 朱炳金. 六硼化镧薄膜的制备及发射特性的研究[D]. 电子科技大学,2008.