The mixture of pure Zn powder (99.99%) and Mg block (99.99%) in a weight
ratio of 4:1 was placed in an alumina crucible and melted at 800 C in a furnace
under air ambient. Then the melt was stirred using an alumina rod. After the furnace
was cool down to room temperature, the Zn and Mg alloys were divided into
many small blocks used as the source materials to synthesize Zn1xMgxO nanomaterials.
Energy dispersive X-ray (EDX) analysis confirmed that the molar ratio of Mg
in the Zn and Mg alloys source material is 13.26%. Zn1xMgxO nanomaterials were
synthesized by chemical vapor deposition method in a horizontal tube furnace. The
experimental setup is schematically demonstrated in Fig. 1(a). The Zn and Mg alloys
were loaded into a quartz boat placed at the end of a one-end sealed quartz tube
with 2 cm in diameter. Quartz substrates were placed about 20 cm away from
the source material to receive the products. Then the quartz tube was inserted into
the horizontal tube furnace and made the sealed end at the center of the furnace
tube. After that, the tube furnace was evacuated by using a mechanical rotary pump
to remove the residual oxygen and was heated to appropriate temperatures of 750,
850, 900 and 1000 C, respectively, at a rate of 15 C/min. As soon as it reached the
desired temperature, we stopped the evacuation of the mechanical rotary pump,
keep the system for 2 min at the growth temperature, then introduced the
mixed-gas of argon and oxygen with a ratio of 2:1 into the furnace system, at the
same time, we open the vent valve to make the mixed-gas naturally flow out.
The growth time is 50 min. Prior to the growth, the quartz substrate was treated
with ethanol in an ultrasonic bath to remove surface contamination and etched
in HCl solution at 80 C for 10 min, and then rinsed in deionized water and lown
dry using high-purity nitrogen. The yellowish powder on the quartz substrate could
be obtained after the furnace was cooled to room temperature naturally. As a comparison,
the pure ZnO nanoparticles without Mg dopant were also synthesized at
750 C under the same condition, the pure Zn metal was used as source material.
The morphology and structure of the Zn1xMgxO nanostructures were characterized
using a field emission scanning electron microscope (FE-SEM; Philips
XL30FEG) with an accelerating voltage of 5 kV, X-ray diffraction (XRD) measurement
was performed by using a RigakuO/max-RA X-ray diffractometer with Cu
Kal radiation (k = 0.15418 nm). Energy dispersive X-ray (EDX) analysis was also
performed during the FE-SEM observation. The micro-Raman in the backscattering
geometry and photoluminescence (PL) spectra were recorded at room temperature
by a Jobin Yvon LabRAM HR800UV micro-Raman system under an Ar+ (514.5 nm)
and a He–Cd (325.0 nm) laser excitation, respectively. Optical absorption spectra
were recorded by using a UV-3101PC spectrometer
The mixture of pure Zn powder (99.99%) and Mg block (99.99%) in a weight
ratio of 4:1 was placed in an alumina crucible and melted at 800 C in a furnace
under air ambient. Then the melt was stirred using an alumina rod. After the furnace
was cool down to room temperature, the Zn and Mg alloys were divided into
many small blocks used as the source materials to synthesize Zn1xMgxO nanomaterials.
Energy dispersive X-ray (EDX) analysis confirmed that the molar ratio of Mg
in the Zn and Mg alloys source material is 13.26%. Zn1xMgxO nanomaterials were
synthesized by chemical vapor deposition method in a horizontal tube furnace. The
experimental setup is schematically demonstrated in Fig. 1(a). The Zn and Mg alloys
were loaded into a quartz boat placed at the end of a one-end sealed quartz tube
with 2 cm in diameter. Quartz substrates were placed about 20 cm away from
the source material to receive the products. Then the quartz tube was inserted into
the horizontal tube furnace and made the sealed end at the center of the furnace
tube. After that, the tube furnace was evacuated by using a mechanical rotary pump
to remove the residual oxygen and was heated to appropriate temperatures of 750,
850, 900 and 1000 C, respectively, at a rate of 15 C/min. As soon as it reached the
desired temperature, we stopped the evacuation of the mechanical rotary pump,
keep the system for 2 min at the growth temperature, then introduced the
mixed-gas of argon and oxygen with a ratio of 2:1 into the furnace system, at the
same time, we open the vent valve to make the mixed-gas naturally flow out.
The growth time is 50 min. Prior to the growth, the quartz substrate was treated
with ethanol in an ultrasonic bath to remove surface contamination and etched
in HCl solution at 80 C for 10 min, and then rinsed in deionized water and lown
dry using high-purity nitrogen. The yellowish powder on the quartz substrate could
be obtained after the furnace was cooled to room temperature naturally. As a comparison,
the pure ZnO nanoparticles without Mg dopant were also synthesized at
750 C under the same condition, the pure Zn metal was used as source material.
The morphology and structure of the Zn1xMgxO nanostructures were characterized
using a field emission scanning electron microscope (FE-SEM; Philips
XL30FEG) with an accelerating voltage of 5 kV, X-ray diffraction (XRD) measurement
was performed by using a RigakuO/max-RA X-ray diffractometer with Cu
Kal radiation (k = 0.15418 nm). Energy dispersive X-ray (EDX) analysis was also
performed during the FE-SEM observation. The micro-Raman in the backscattering
geometry and photoluminescence (PL) spectra were recorded at room temperature
by a Jobin Yvon LabRAM HR800UV micro-Raman system under an Ar+ (514.5 nm)
and a He–Cd (325.0 nm) laser excitation, respectively. Optical absorption spectra
were recorded by using a UV-3101PC spectrometer
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