Relaxation effects in a composite on the basis of trikadmy diarsenide at high pressure
At a Glance
Section titled “At a Glance”| Metadata | Details |
|---|---|
| Publication Date | 2018-01-01 |
| Journal | HERALD of Dagestan State University |
| Authors | Nataliya V. Melnikova, L. A. Saipulaeva, А. Г. Алибеков, M. M. Gadzhialiev, V.S. Zakhvalinsky |
| Institutions | Belgorod National Research University, Dagestan Scientific Center of the Russian Academy of Sciences |
| Analysis | Full AI Review Included |
Technical Analysis of Relaxation Effects in $\text{Cd}{3}\text{As}{2}/\text{MnAs}$ Composites under High Pressure
Section titled “Technical Analysis of Relaxation Effects in $\text{Cd}{3}\text{As}{2}/\text{MnAs}$ Composites under High Pressure”Executive Summary
Section titled “Executive Summary”This documentation summarizes the key findings and methodologies of the research paper “Relaxation effects in a composite on the basis of trikadmy diarsenide at high pressure,” focusing on its implications for high-pressure materials science and advanced diamond engineering.
- Core Research Focus: Investigation of electrical resistance ($\text{R}$) and thermoelectric power (Seebeck coefficient, $\text{S}$) relaxation phenomena in the Dirac semimetal composite $(\text{Cd}{3}\text{As}{2}){0.653}(\text{MnAs}){0.44}$ under quasi-hydrostatic pressure up to 50 GPa.
- Experimental Setup: High-pressure environment achieved using a Diamond Anvil Cell (DAC) featuring a specialized “rounded cone-plane” geometry and anvils made from artificial “carbonado” diamond material.
- Critical Phase Transition Detected: A significant and abrupt increase in the relaxation times ($\text{t}{\min}$ and $\text{t}{0}$) of both $\text{R}$ and $\text{S}$ was observed precisely within the narrow pressure range of P $\approx$ 30-33 GPa.
- Interpretation: This pronounced relaxation effect is interpreted as evidence of a room-temperature electronic or structural phase transition, primarily linked to changes in the electronic subsystem characteristics of the $\text{Cd}{3}\text{As}{2}$ matrix.
- Thermoelectric Performance: The magnitude of the Seebeck coefficient ($\text{S}$) increased dramatically, reaching 4 to 4.5 times the original value when pressure was raised to 50 GPa, highlighting pressure as a powerful tuning parameter for transport properties.
- Relevance to 6CCVD: The study relies heavily on high-quality diamond anvils and precise micro-fabrication, directly aligning with 6CCVD’s expertise in MPCVD Single Crystal Diamond (SCD) components for extreme environments.
Technical Specifications
Section titled “Technical Specifications”The following table summarizes the hard data points and experimental parameters critical to the reported high-pressure measurements.
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Maximum Applied Pressure | 50 | GPa | Quasi-hydrostatic limit for measurements. |
| Key Transition Pressure Range | 30 - 33 | GPa | Region showing maximum relaxation time increase ($\text{t}{\max}/\text{t}{\text{p}}$ peak). |
| Secondary Transition Pressure | 4.4 | GPa | Observed structural phase transition (confirming prior work). |
| Sample Thickness | 10 - 30 | µm | Dimensions of the compressed composite sample. |
| Sample Diameter | ~0.2 | mm | Required dimension for the high-pressure cell. |
| Maximum Seebeck Increase | 4 - 4.5 | times | Relative increase of $\text{S}$ at 50 GPa compared to initial pressure. |
| Relaxation Time (t${0}$, t${min}$) Range | 5 - 8 | s | Observed at P $\approx$ 33 GPa and up to ~45 GPa. |
| Estimated Carrier Concentration (n) | 1021 - 1022 | cm-3 | Calculated from Seebeck data, indicative of a degenerate semiconductor/semimetal. |
| High Pressure Anvil Type | ”Carbonado” | N/A | Type of artificial diamond used for the anvil cells. |
| Thermocouple Material | $\text{Cu-Constantan}$ | N/A | Used for monitoring $\text{T}{1}$ and $\text{T}{2}$ at the anvil contacts. |
Key Methodologies
Section titled “Key Methodologies”The experiment utilized specialized high-pressure techniques to measure transport properties and relaxation phenomena under extreme conditions.
- Pressure Generation: Quasi-hydrostatic pressure up to 50 GPa was generated using a high-pressure chamber (KVD) equipped with diamond anvils configured in a “rounded cone-plane” geometry.
- Sample Preparation: The $(\text{Cd}{3}\text{As}{2}){0.653}(\text{MnAs}){0.44}$ composite was pressed into very small, thin discs (10-30 µm thickness, 0.2 mm diameter) directly within the DAC.
- Electrical Resistance ($\text{R}$) Measurement: Resistance was measured using a constant DC current, tracking its dependence on pressure ($\text{R}(\text{P})$) during both compression (upload) and decompression (unload) cycles.
- Thermoelectric Power ($\text{S}$) Measurement: A thermal gradient ($\text{T}{1} \text{ - } \text{T}{2}$) was created by heating one of the diamond anvils.
- Temperature Monitoring: Temperatures at the contact points of the anvils were precisely monitored using two separate $\text{Cu-Constantan}$ thermocouples.
- Relaxation Analysis: Time-dependent relaxation effects were analyzed upon pressure stabilization:
- $\text{R}(t)$ relaxation was fitted using a double exponential function ($\text{R}(t) = \text{A}{1}\text{e}^{-t/t{1}} + \text{A}{2}\text{e}^{-t/t{2}}$) to identify shorter ($\text{t}{\min}$) and longer ($\text{t}{\max}$) relaxation times.
- $\text{S}(t)$ relaxation was approximated by a single exponential function ($\text{S}(t) = \text{A}\text{e}^{-t/t_{0}}$).
- Cycling: Measurements were often performed using pressure cycling schemes to observe hysteretic effects and ensure phase stability.
6CCVD Solutions & Capabilities: Enabling Extreme Pressure Research
Section titled “6CCVD Solutions & Capabilities: Enabling Extreme Pressure Research”The study of complex materials like Dirac semimetals under extreme pressure (DAC research) demands diamond components with exceptional purity, strength, and customized geometries. 6CCVD is uniquely positioned to supply the next generation of MPCVD diamond tools required to replicate and extend this research beyond 50 GPa.
| Application Requirement | 6CCVD Material Solution | Customization & Engineering Capability |
|---|---|---|
| High-Pressure Anvils (50+ GPa) | Optical Grade Single Crystal Diamond (SCD) | Our MPCVD SCD (up to 500 µm thickness) provides superior strength and crystallographic perfection necessary to withstand pressures far exceeding 50 GPa. Low-strain, nitrogen-free Type IIa material ensures maximum mechanical integrity and reliability. |
| Integrated Heating & Sensing | Boron-Doped Diamond (BDD) Films | For creating integrated heating circuits or reliable electrical contacts directly on the anvil face, 6CCVD supplies precisely doped BDD films (thickness 0.1 µm to 500 µm) with controlled conductivity, replacing traditional, less stable metal films. |
| Precision Geometry & Micro-Fabrication | Custom Dimensions & Laser Cutting | Replicating the “rounded cone-plane” geometry or fabricating intricate micro-gasket components (like the 0.2 mm diameter sample space) is handled in-house. We guarantee micron-level precision and custom geometries up to 125 mm diameter (PCD). |
| Electrical Contact Layers | Advanced Metalization Services | To ensure reliable $\text{R}$ and $\text{S}$ measurements and thermocouple contacts (as required in the paper), 6CCVD offers custom thin-film deposition of high-performance metals including Ti, Pt, Au, W, Pd, and Cu directly onto SCD or PCD substrates. |
| Surface Quality | Ultra-Smooth Polishing | Achieving reliable thermal and electrical contact requires unparalleled surface finish. Our SCD polishing achieves Ra < 1 nm, critical for minimizing parasitic resistances and ensuring uniform pressure distribution across the anvil tips. |
Engineering Support & Delivery Promise
Section titled “Engineering Support & Delivery Promise”To successfully conduct high-pressure studies involving sensitive relaxation phenomena, the quality of the diamond components is paramount. 6CCVD’s in-house PhD engineering team specializes in the application requirements of high-pressure physics, particularly in optimizing material selection (SCD vs. PCD, doping levels, optical quality) for specific pressure ranges and measurement types (e.g., maximizing transparency for optical/IR measurement, or conductivity for thermoelectric projects like this $\text{Cd}{3}\text{As}{2}/\text{MnAs}$ study).
We ensure secure, reliable, global shipping (DDU default, DDP available), providing researchers worldwide with access to cutting-edge MPCVD diamond technology.
For custom specifications or material consultation related to high-pressure DAC experiments, Dirac semimetals, or advanced transport physics, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
The article studies the pressure behavior of the electrical resistance and thermopower in a wide range of pressures (up to 50 GPa) at room temperature and relaxation effects arising during the formation of new phases are investigated.The object of research was the composite tricadmiumdiarsenide -manganese arsenide consisting of granules of ferromagnetic MnAs, placed in a semiconductor matrix tricadmiumdiarsenide.To create quasi-hydrostatic pressures, a high-pressure chamber with diamond anvils of the “rounded cone-plane” type was used.To create a temperature gradient, one of the anvils was heated; the temperature of the anvils at the contact points was measured by two copperconstantan thermocouples.The analysis of the dependence of the relaxation time in the electrical resistivity on pressure made it possible to establish that under the interval of 30-33 GPa a significant increase in the relaxation time of the electrical resistivity due to a possible structural or electronic phase transition is observed.