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High-pressure cells for low-temperature neutron scattering at ISIS

ISIS 低温中子散射高压室

基本信息

批准号：
ST/F001495/1
负责人：
Konstantin Kamenev
金额：
$ 57万
依托单位：
University of Edinburgh
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2008
资助国家：
英国
起止时间：
2008 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=ST%2FF001495%2F1
关键词：
pressure cells low temperature neutron

项目摘要

We propose to combine high-pressure, low-temperature and neutron diffraction techniques for studies of materials, enabling ISIS to achieve new extremes of high-pressure and low-temperature. The ability to study materials at elevated pressures allows researchers to modify many of their properties and to recreate the conditions existing in deep earth or on other planets. Very low temperatures are needed to study magnetic and other quantum phenomena in solids. Neutron scattering is the ideal tool for magnetic and many structural ordering phenomena. The proposed research is focused on combining these three components by developing high-pressure cells suitable for neutron diffraction studies working at temperatures down to a few tenths of a degree above absolute zero while achieving pressures of 10 GPa or more. The design of the pressure cells will be based on the opposed-anvil principle, in which the studied sample is squeezed between two hard anvils while supported by a metal gasket on its sides. It is important for neutron scattering to have as much sample as possible in the neutron beam and so large anvils will be needed for these pressure cells. The hardest known material is diamond, but large diamonds are forbiddingly expensive and may not be available. We therefore propose to use in the initial stages relatively inexpensive large silicon carbide (moissanite) anvils. Silicon carbide has a Mohs hardness of 9.25 (diamond has 10 on the same scale) and moissanite pressure cells are reported to achieve pressures of up to 60 GPa (approximately 600,000 atm). To accomplish this, it is important that the shape of the anvils is optimised in order to achieve maximum possible pressures without breaking and that their alignment with respect to each other and the pressure cell is perfect. Therefore, part of the proposed research will be focused on using the powerful technique of finite element analysis (FEA) for optimising the shape of the anvils. Using FEA will not only help to speed up the project and find the right shape for the anvils but will minimise anvil breakages in trial experiments. FEA, combined with computer aided design (CAD), will also help to design the pressure cells themselves and make sure that they will fit into the cryogenic equipment and are aligned with the detectors. Another important feature of the proposed pressure cells is the ability of the operator to change the pressure while the cell is inside the cryostat and measure the pressure inside the cell at the same time via a fibre optic cable. This will be very useful for changing pressure at constant low temperature, which is not possible with present technologies. This saves time in not having to warm the cell up to room temperature to change pressure and, then having to realign the sample inside the cell at each new pressure. The cells will initially be used to study ordering transitions in model systems such as multiferroic materials, manganese oxides exhibiting colossal magnetoresistance and magnetic rare earth oxosalts with complex spin structures arising from frustration.

我们建议将联合收割机高压、低温和中子衍射技术结合起来用于材料研究，使ISIS能够实现高压和低温的新极限。在高压下研究材料的能力使研究人员能够修改它们的许多性质，并重现地球深处或其他行星上存在的条件。研究固体中的磁性和其他量子现象需要非常低的温度。中子散射是研究磁性和许多结构有序现象的理想工具。拟议的研究重点是通过开发适用于中子衍射研究的高压电池将这三个组件结合起来，这些电池在绝对零度以上零点几度的温度下工作，同时达到10 GPa或更高的压力。压力传感器的设计将基于对置砧原理，其中所研究的样品在两个硬砧之间挤压，同时在其侧面由金属垫圈支撑。对于中子散射来说，在中子束中有尽可能多的样品是很重要的，因此这些压力室将需要大的砧座。已知最硬的材料是钻石，但大钻石价格昂贵，可能无法获得。因此，我们建议在初始阶段使用相对便宜的大型碳化硅（碳硅石）砧。碳化硅具有9.25的莫氏硬度（金刚石在相同尺度上具有10），并且据报道碳硅石压力单元实现高达60GPa（约600，000atm）的压力。为了实现这一点，重要的是，砧座的形状被优化，以便在不断裂的情况下实现最大可能的压力，并且它们相对于彼此和压力单元的对准是完美的。因此，部分拟议的研究将集中在使用有限元分析（FEA）的强大技术，优化砧的形状。使用有限元分析不仅有助于加快项目进度并找到合适的砧座形状，还可以最大限度地减少试验中的砧座断裂。有限元分析与计算机辅助设计（CAD）相结合，也将有助于设计压力单元本身，并确保它们适合低温设备并与探测器对齐。所提出的压力传感器的另一个重要特征是操作者能够在传感器位于低温恒温器内时改变压力，并同时通过光纤电缆测量传感器内的压力。这对于在恒定低温下改变压力非常有用，而这在现有技术中是不可能的。这节省了时间，因为不必将单元加热到室温来改变压力，然后不必在每个新的压力下重新对准单元内的样品。这些细胞最初将用于研究模型系统中的有序转变，例如多铁性材料，表现出巨大磁阻的锰氧化物和具有复杂自旋结构的磁性稀土含氧盐。

项目成果

期刊论文数量（7）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

High-pressure cell for neutron diffraction with in situ pressure control at cryogenic temperatures.

用于中子衍射的高压室，可在低温下进行原位压力控制。

DOI：
10.1063/1.4870061
发表时间：
2014
期刊：
The Review of scientific instruments
影响因子：
0
作者：
Jacobsen MK
通讯作者：
Jacobsen MK

High pressure neutron and X-ray diffraction at low temperatures

DOI：
10.1515/zkri-2013-1673
发表时间：
2014
期刊：
影响因子：
0
作者：
C. Ridley;K. Kamenev
通讯作者：
C. Ridley;K. Kamenev

Colossal negative thermal expansion in BiNiO3 induced by intermetallic charge transfer.

DOI：
10.1038/ncomms1361
发表时间：
2011-06-14
期刊：
NATURE COMMUNICATIONS
影响因子：
16.6
作者：
Azuma, Masaki;Chen, Wei-tin;Seki, Hayato;Czapski, Michal;Olga, Smirnova;Oka, Kengo;Mizumaki, Masaichiro;Watanuki, Tetsu;Ishimatsu, Naoki;Kawamura, Naomi;Ishiwata, Shintaro;Tucker, Matthew G.;Shimakawa, Yuichi;Attfield, J. Paul
通讯作者：
Attfield, J. Paul

Large volume high-pressure cell for inelastic neutron scattering.

用于非弹性中子散射的大体积高压室。