Furnaces by Scientific Instruments Dresden –
Floating Zone, Oxygen and Multi-Gas Furnaces

High-Pressure High-Temperature Optical Floating Zone Furnace HKZ

The abbreviation HKZ (Hochdruck-Kristallzüchtungsanlage) stands for a unique high-pressure optical floating zone crystal growth furnace. It features a vertical 2-mirror setup with a highly homogeneous and controllable light power distribution on the crystal rod. One of the key characteristics of the furnace is the ability to work at pressures of up to 150 bar with different gases and mixtures in the growth chamber. Additionally, individual gas flow rates can be adjusted and controlled freely and independently over the complete pressure range.

Using powerful xenon short arc lamps, melting temperatures over 3000 °C can be achieved. While the light power tuning range of arc lamps is limited, the thermal energy in the growth chamber is step-less adjustable between 0 and 100%, thanks to a power shutter system in the light beam. Highly precise, magnetically coupled linear and rotation feed through systems with pulling rates starting from 0.1 mm/h, advanced process monitoring technologies, and a comfortable PLC user interface guarantee extensive control of the growth process. The temperature of feed rod, melt zone and crystal is measured directly via a patented in-situ temperature measurement system. An optional after-heater is applicable with all possible atmospheres and pressures—also with high-pressure oxygen atmospheres.

Technical details

Atmosphere

• Argon and oxygen (pure and in any mixture ratio)
• Many other gases possible on request
• Pressure: up to 300 bar (available versions: 10 bar, 50 bar, 150 bar, 300 bar)
• Turbulence suppression system
• PLC controlled gas flow: 0.25 l/min to 1 l/min, individually adjustable for different gases
• Vacuum: down to 1x10^-5 mbar
• Turbo pump close to the process chamber, wide diameter connections
• UHV system possible on request
• Active titanium getter gas cleaning (removes O₂ traces in argon down to 10^-12 ppm, applicable under high-pressure conditions)
• Oxygen content measurement system

Growth chamber

• Highly transparent material
• Pressure-proved between 0 and max. pressure (up to 300 bar)
• Long life span due to protective tube
• Sample holder for 6.8 mm or 9.8 mm samples

Optical heating

• Xenon short arc lamp (different kinds available between 3 kW and 15 kW)
• Temperature: up to 3000 °C
• Lamp power control
• Power shutter in the light beam, step-less adjustable between 0 and 100%
• Precise motor-driven lamp positioning unit, workable during the experiment
• Upper and lower optimized elliptical mirrors, aluminum or gold coated
• Mirror position adjustment system

Material rod moving

• Precise magnetically coupled linear and rotation feed through system
• Pulling rate: 0.1 mm/h to 200 mm/h (lower pulling rates possible on request)
• Fast service gear (approx. 0.6 mm/s )
• Pulling length: 195 mm
• Rotation rate: 0 to 70 rpm

Temperature measurement

• Two-color pyrometer with a patented stroboscopic measurement method
• Adjustable time interval
• Adjustable position
• Several temperature ranges

After-heater

• Versatile and modular unit
• Applicable with all possible atmospheres and pressures
• Easily exchangeable heater coils
• Highly adaptable to special needs

Process control and monitoring

• High-resolution CCD camera with specialized lenses and filters
• Monitoring application: visual control, video recordings, snapshots and length measurements during the growth process
• Power ramp and traveling ramp functions
• Front window for direct observation of the growth chamber
• All system parameters are controllable and adjustable via a PLC-based software application with two 27" touch screens
• Safety system with protection housing, door lock system, automatic shutdown function

Laboratory requirements

• Gas supply with the intended pressure
• Exhaust air system
• Energy supply: 3-phase AC, 50 Hz, 400 V, 63 A
• Cooling water

Furnace dimensions

• Height: 3020 mm , Width: 1631 mm, Depth: 920 mm

 

Advanced High-Pressure Oxygen Furnace

Some material states with highly interesting properties are only stable under high temperatures and high pressure atmospheres with a precisely defined partial pressure of oxygen. During cooling and releasing the pressure to ambient conditions or changing the oxygen content in the atmosphere, these elusive states often decompose, making the analysis of their physical properties almost impossible. By quenching the sample within milliseconds under defined high pressure atmospheres, the metastable material states freeze and their properties remain under ambient conditions.

With the "Quenching and Gas Management Upgrade" to our High Pressure Oxygen Furnace we create an instrument, which combines the possibility to rapidly quench the sample, treat the sample under high temperatures, enable high gas pressures, and have full control of oxygen content in the process atmosphere between 0 and 100%.

The A-HSO is set up to operate vertically. The sample is mounted in a hanging position within the heating zone of the process chamber. When the sample is ready to be quenched, the mounting system is released and the sample drops into a quenching chamber, which is located underneath. The release of the sample mounting system and the drop of the sample can be triggered manually or automatically (e.g., after a certain amount of time or other measured value thresholds). The lower chamber is filled with the same atmosphere as the process chamber and is valved off with a rapidly operating automatic gate valve. During the process, the atmosphere around the sample can be freely adjusted in terms of total pressure, gas mixture and individual gas flow rates. The elaborated gas management system includes precise mass flow controllers for each gas and allows in-situ manual or automatic changes to the process atmosphere at any time during the process. A precise thermocouple element sits near the sample and a set of additional thermocouples monitors the furnace temperature in different places. All experimental parameters such as furnace and sample temperatures, gas pressure, mixture and flow as well as the release of the sample mounting system are controlled by a build-in computer.

Technical details

Atmosphere

• Process chamber gas:  oxygen and argon (pure and in any mixture)
• Many other gases possible on request
• Pressure: 1 to 200 bar
• Automatically controlled gas flow up to 1 l/min (higher flow rates possible on request)
• Each gas adjustable independently with an individual mass flow controller
• Precise oxygen content measurement system
• Automated pressure control while heating and cooling

Heating

• Specialized resistive heating elements
• Long life span due to protective environment
• Maintenance-free operation
• Maximum temperature: 1200 °C (higher temperatures possible on request)

Process chamber

• Dimensions: diameter 25 mm, heating zone length 200 mm
• Chamber material: non-reactive material withstanding high-pressure oxygen under high temperatures
• Precise thermocouple element for permanent temperature monitoring

Process control

• Build-in computer unit with touchscreen for all controlling purposes
• Fully automatic or manual operation
• Power ramp functions with several temperature steps and heating/cooling rates adjustable
• Pressure pump functions with several pressure steps and rates adjustable  
• Permanent data logging function

Quenching upgrade

• Sample release system, automatically or manually triggered at any time
• Lower quenching chamber filled with water or other quenching media
• Lower chamber separated by an automatically operated gate valve

Laboratory requirements

• 210 bar oxygen and argon gas supply with constant pressure rate
• Energy supply: AC single phase 220-240 V
• Cooling water with approx. 20 °C,  pressure up to 3 bar, min. 4 liter/min, 4000 W cooling power

 

High Pressure Multi-Gas Furnace

The high-pressure multi-gas sintering furnace HMO allows heat treatment of materials under different atmospheres and enhanced pressures. It covers the range from sintering rods for crystal growth to maintaining phases which are only stable at higher pressures. Furnace can be used to retreat materials after crystal growth at high pressures up to 150 bar and at temperatures up to 1000°C.

The furnace is equipped with a special alloy tube offering an inner diameter of 15 mm and a heating zone of 200 mm with a low temperature deviation. The furnace setup with separated process and heating chambers allows the usage of almost any aggressive media and guarantees a long life span of the heating elements.

Gases that can be used:

• O₂
• H₂
• N₂
• CO
• CO₂
• CO/CO₂-mixtures
• H₂/H₂O-mixtures
• Ar
• He
• Forming gas N₂/H₂; Ar/H₂
• Further gases on request