Stable magnesium peroxide at high pressure

At a Glance

Metadata	Details
Publication Date	2015-09-01
Journal	Scientific Reports
Authors	Sergey S. Lobanov, Qiang Zhu, Nicholas Holtgrewe, Clemens Prescher, Vitali B. Prakapenka
Institutions	Howard University, V.S. Sobolev Institute of Geology and Mineralogy
Citations	39
Analysis	Full AI Review Included

Technical Documentation & Analysis: High-Pressure Synthesis of $I4/mcm$ MgO$_{2}$

This document analyzes the requirements and methodologies detailed in the research paper “Stable magnesium peroxide at high pressure” and aligns them with the advanced material capabilities offered by 6CCVD, specializing in MPCVD diamond solutions for extreme environments.

Executive Summary

This research successfully synthesized $I4/mcm$ magnesium peroxide (MgO$_{2}$), a potential high-pressure mineral for highly oxidized exoplanetary interiors, utilizing a Laser-Heated Diamond Anvil Cell (LH-DAC).

Core Achievement: Synthesis of $I4/mcm$ MgO${2}$ via reaction between MgO and O${2}$ at extreme conditions.
Extreme Conditions: Stable phase synthesized above 96 GPa and at temperatures up to 2150 K.
Critical Equipment: High-purity Single Crystal Diamond (SCD) anvils were essential for maintaining pressure integrity and providing optical/X-ray windows for in situ characterization.
Material Evidence: Raman spectroscopy confirmed the presence of the peroxide ion (O$_{2}$$^{2-}$) in the synthesized and recovered material, preserved to ambient conditions.
Methodology: Synchrotron X-ray Diffraction (XRD), Raman spectroscopy, and Energy-Dispersive X-ray Spectroscopy (EDS) were used for structural and chemical analysis.
6CCVD Value Proposition: Replication and extension of this high-pressure research requires ultra-robust, low-birefringence SCD anvils, which 6CCVD provides with custom culet dimensions and superior polishing (Ra < 1 nm).

Technical Specifications

The following hard data points were extracted from the experimental results, highlighting the extreme conditions and precise material characteristics achieved.

Parameter	Value	Unit	Context
Maximum Experimental Pressure	160	GPa	Run B2
Synthesis Temperature (Run A1)	2150	K	Laser-heated synthesis of MgO$_{2}$
Diamond Anvil Culet Sizes Used	200, 300/100, 300/80	µm	Required for 100-160 GPa range
X-ray Wavelength	0.3344	Å	Synchrotron XRD measurement
MgO$_{2}$ Tetragonal Lattice Parameter (a)	4.000(1)	Å	Quenched sample (Run A1)
MgO$_{2}$ Tetragonal Lattice Parameter (c)	4.743(5)	Å	Quenched sample (Run A1)
Peroxide Ion Raman Shift (A$_{1g}$)	1037	cm^-1	O-O symmetric stretching vibration at 104 GPa
Oxygen Content (Laser-Heated Area)	64 ± 3	at%	Confirmed by EDS mapping
Laser Heating Wavelength	1064	nm	Used for coupling radiation to oxygen/gold absorber

Key Methodologies

The synthesis and characterization of $I4/mcm$ MgO$_{2}$ relied on precise control within the Diamond Anvil Cell (DAC) environment.

DAC Setup:
- Rhenium (Re) foils (200 µm thick) were indented to 30-40 µm thickness and laser-drilled to create sample chambers (30-100 µm diameter).
- Diamond anvils with culets ranging from 80 µm to 300 µm were used to achieve pressures up to 160 GPa.
Precursor Loading (Type A):
- MgO powder (99.85%) was annealed at 1293 K to remove adsorbed water.
- Two 4-5 µm thick MgO disks were stacked in the gasket hole, which was subsequently filled with liquefied zero-grade oxygen (O$_{2}$) at approximately 77 K.
Precursor Loading (Type B):
- Magnesium peroxide complex (Pa3 MgO$_{2}$, MgO, Mg) was mixed with submicron gold (Au) powder, which served as a laser absorber.
Laser Heating and Synthesis:
- Synthesis was performed using a double-sided laser-heating system (1064 nm laser).
- Oxygen acted as a near-infrared absorber (P > 10 GPa), with efficiency boosted by metallic oxygen (P > 96 GPa) or by the Au absorber (Type B runs).
- Temperature was measured spectroradiometrically with an assumed uncertainty of 150 K.
Characterization Techniques:
- Synchrotron XRD: Collected in situ at high P/T using a 37.077 keV beam focused to a 4 µm spot size. Used for determining phase onset and structural parameters.
- Raman Spectroscopy: Performed on quenched samples using 488 nm, 532 nm, and 660 nm excitation lines focused to 3-4 µm spots to detect the O$_{2}$$^{2-}$ peroxide ion.
- EDS: Used to map the recovered sample (A2) to confirm higher oxygen content in the laser-heated area (64 ± 3 at% O).

6CCVD Solutions & Capabilities

The successful execution of high-pressure research, particularly in LH-DAC systems, is fundamentally dependent on the quality and precision of the diamond anvils. 6CCVD is uniquely positioned to supply the necessary SCD materials to replicate and advance this research.

Applicable Materials: Single Crystal Diamond (SCD)

The extreme pressure (up to 160 GPa) and temperature (2150 K) conditions, combined with the need for high-quality optical and X-ray windows, mandate the use of Optical Grade Single Crystal Diamond (SCD).

High Purity SCD: Essential for minimizing absorption and scattering during laser heating and synchrotron XRD/Raman analysis.
Low Birefringence: Critical for high-quality optical access (Raman, spectroradiometry) by reducing signal distortion caused by stress-induced birefringence under extreme pressure.
Thermal Management: The paper notes that diamond’s remarkable thermal conductivity keeps the diamond-sample interface near ambient temperature. 6CCVD’s high-purity SCD ensures maximum thermal dissipation, protecting the DAC components and maintaining experimental stability.

Customization Potential for High-Pressure Research

6CCVD’s MPCVD capabilities directly address the specialized requirements of DAC experiments:

Requirement from Paper	6CCVD Capability	Technical Specification
Custom Culet Dimensions	Standard offering for DAC anvils.	Plates/wafers up to 125 mm, custom laser cutting for culets (e.g., 80 µm, 100 µm, 300 µm) and specific anvil geometries.
Optical Quality	Superior polishing and surface finish.	SCD polishing to Ra < 1 nm for optimal optical transmission and minimal signal loss during Raman and spectroradiometric measurements.
Thickness Control	Precise material growth control.	SCD thickness available from 0.1 µm up to 500 µm, allowing researchers to select optimal anvil thickness for specific pressure ranges.
Laser Absorber Integration	Custom metalization services.	While Au powder was used here, 6CCVD offers internal metalization (Au, Pt, Ti, W) for creating integrated heating elements or contact layers on the diamond surface for electrical conductivity studies under pressure.
Global Logistics	Reliable, secure shipping.	Global shipping available (DDU default, DDP available) to ensure timely delivery of critical components to synchrotron facilities worldwide (e.g., APS, as used in this study).

Engineering Support

6CCVD’s in-house PhD team specializes in the material science of diamond under extreme conditions. We can assist researchers in selecting the optimal SCD grade, orientation, and geometry to maximize the pressure range and optical clarity for similar high-pressure mineral physics and planetary science projects.

For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.

Tech Support

Original Source

DOI: https://doi.org/10.1038/srep13582