Leveraging oxide reactive sputtering for thermal insulation in laser-heated diamond anvil cell

Figures & data

Figure 1. Schematic of the radiofrequency magnetron sputtering machine used in this study.

Figure 2. (a) Optical microscope image of the deposited alumina layer on the diamond anvil surface in run A8 with a scale of 100 μm. The bright spot on the left side of the culet is due to the oblique incident light from the optical microscope. (b,c) Secondary electron microscope image of cross-sections of (b) alumina and (c) zirconia layers on a single crystal diamond substrate milled by focused ion beam in run A9 and A10, respectively. Gold was deposited on top of the ZrO₂ layer to prevent charge-up.

Table 1. Size of the radiofrequency magnetron sputtering machine.

Parts	Dimension	Size (mm)
Vacuum chamber	Inner diameter	210
	Height	200
	Groove diameter	65
	Groove depth	35
Metal/oxide target	Diameter	50
Aperture	Diameter	65
	Height from target	45
	Hole diameter	17

Table 2. Conditions and results of alumina and zirconia sputtering.

Run #	Target	Aperture	Substrate	Culet size (µm)	Distance^b (mm)	Pchamber (Pa)	rO2^c (%)	Power (W)	Time (min)	rP ^c (%)	Film color	Film thickness (μm)
A1	Al	none	slide glass	–	170	0.3	14.8	80	30	−0.6	opaque	–
A2	Al	none	slide glass	–	170	0.3	16.4	80	30	0.3	translucent	–
A3	Al	none	Diamond^a	–	170	0.3	17.3	80	30	0.0	translucent	–
A4	Al	none	slide glass	–	170	0.3	17.9	80	30	1.6	translucent	–
A5	Al	none	slide glass	–	170	0.3	17.9	80	30	3.6	translucent	–
A6	Al	none	slide glass	–	170	0.3	18.7	80	30	10	transparent	–
A7	Al2O3	none	diamond^a	flat 300	80	0.9	45.5	100	660	–	transparent	> 1.0^d
A8	Al	used	diamond^a	flat 300	80	0.4	8	100	90	–	transparent	–
A9	Al	used	diamond^a	flat 300	80	0.4	8	100	180	–	transparent	2.0^e
A10	Zr	used	diamond^a	flat 300	100	0.4	8.7	100	160	–	transparent	1.2^e
B1	Al	used	diamond^a	beveled 200	80	0.4	8	100	180	–	transparent	2.0^f
	Zr	used	diamond^a	beveled 200	100	0.4	8.7	100	270	–	transparent	2.0^f
B2	Zr	used	diamond^a	beveled 120	100	0.4	8.7	100	300	–	transparent	2.3^f

^a Deposited on (100) plane of single crystal diamond.

^b Distance between a sputtering target and a substrate surface.

^c See Eqs. (1) and (2) in the main text.

^d Measured by optical microscope observation.

^e Measured by electron microscope observation on cross section made by FIB.

^f Calculated from deposition rate of 0.67 μm/hour for alumina and 0.45 μm/hour for zirconia.

Figure 3. The laser power-temperature relations when sputtered (a) 2 μm-thick alumina and zirconia layers in run B1, and 2.3 μm-thick zirconia layer in run B2 at (b) 91 GPa, and (c) 60 GPa.