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Effect of Metal Ions on the Growth and Character of ZnO Crystals

Author: WangWeiWei
Tutor: WeiZhiRen
School: Hebei University
Course: Optical Engineering
Keywords: ZnO crystal hydrothermal method DMS morphology magnetism
CLC: O484.1
Type: Master's thesis
Year: 2007
Downloads: 49
Quote: 0
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Abstract


In this paper, the ZnO Crystals of diluted magnetic doping(Mn2+、Co2+) and other ions(such as Sn2+、In3+、Cu2+) codoping were synthrsized by hydrothermal method. These experiments were finished by mineralizer of 3mol/L KOH, the fill factor of 35%,reaction temperature of 430℃,and time of 24 hours.When mineradizer added to Mg2+ or Ca2+, the rate of growth along c-axic was weakened obviously. And the obtained ZnO crystals can expose more area on the positive polar face c{0001}.The alkaline earth metal ions can reduce crystals disfigurement and keep high quality. In3+ in ZnO not only improve crystals shape, the obtained ZnO facies is slick and structure is intact, show regular symmetrically hexagon, But also greatly increase the charge carrier concentration. The n-type ZnO crystals were first obtained by hydrothermal method.Through adjust different doping elements, all kinds of codoped ZnO are gained. The content of transition metal ions in the sample crystal is surveyed with X-ray energy spectrum. It showed that the ions of Mn、Co can be easily doped in and achieve high content, but Sn、In、Cu were hardly dope in ZnO lattice due to charge and volume compensation.The magnetic properties of these crystals were investigated using a SQUID magnetometer. The Mn and Co、Cu、Sn codoped ZnO crystals do not show room temperature ferromagnetism, presenting antiferromagnetism and high temperature paramagnetism. The Curie temperature is about 50K. The Co、Cu codoped ZnO crystal’s magnetic moment vary unobviously as the temperature rises under 300K. And Co、Sn codoped ZnO show a weak hysteresis cycle, but do not magnetic saturation,It is paramagnetism and ferromagnetism coexist.The single Sn doped crystals show many different shapes with the different doped concentration. Sn ions can control effectively the rate of growth along c-axis. When Sn doped amaunt is over 2%, there were a few club-shaped SnO2 crystals. The results of magnetic measurement show paramagnetism. When precursor materials were changed to Zn(OH)2, the ZnO crystals show icecream shape, These crystals morphology directly reflect growth process of polarity and self-perfect property.

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CLC: > Mathematical sciences and chemical > Physics > Solid State Physics > Thin Film Physics > Film growth,structure and epitaxy
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