NXiv_temp

Status:

application definition, extends NXobject

Description:

Application definition for temperature-dependent IV curve measurements.

In this application definition, times should be specified always together with an UTC offset.

This is the application definition describing temperature dependent IV curve measurements. For this a temperature is set. After reaching the temperature, a voltage sweep is performed. For each voltage a current is measured. Then, the next desired temperature is set and an IV measurement is performed. The application definition defines: - elements of the experimental instrument - calibration information if available - parameters used to tune the state of the sample - sample description

Symbols:

Variables used throughout the document, e.g. dimensions and important parameters

N_data_points: Number of elements in the scanned voltage array

N_variables: Number of additional variables that are changed with the temperature (can be understood as columns next to the temperature)

N_different_temperatures: Number of different temperatures that are set

Groups cited:

NXdata, NXentry, NXenvironment, NXinstrument, NXprocess, NXsample, NXsensor, NXsubentry, NXuser

Structure:

ENTRY: (required) NXentry

@version: (required) NX_CHAR

Version number to identify which definition of this application definition was used for this entry/data.

definition: (required) NX_CHAR

NeXus NXDL schema to which this file conforms.

Obligatory value: NXiv_temp

@url: (optional) NX_CHAR

URL where to find further material (documentation, examples) relevant to the application definition

experiment_identifier: (required) NX_CHAR

Unique identifier of the experiment, such as a (globally persistent) unique identifier. The identifier is usually defined by the facility or principle investigator. The identifier enables to link experiments to e.g. proposals.

experiment_description: (required) NX_CHAR

Description of the exact experiment performed.

start_time: (recommended) NX_DATE_TIME

UTC offset should be specifiec.

PROCESS: (optional) NXprocess

Define the program that was used to generate the results file(s) with measured data and metadata.

program: (required) NX_CHAR

Commercial or otherwise defined given name of the program (or a link to the instrument software).

@version: (required) NX_CHAR

Either version with build number, commit hash, or description of an (online) repository where the source code of the program and build instructions can be found so that the program can be configured in such a way that result files can be created ideally in a deterministic manner.

@program_url: (recommended) NX_CHAR

Website of the software.

operator: (required) NXuser

Contact information of at least the user of the instrument or the investigator who performed this experiment. Adding multiple users if relevant is recommended.

name: (required) NX_CHAR

Name of the user.

affiliation: (required) NX_CHAR

Name of the affiliation of the user at the point in time when the experiment was performed.

address: (required) NX_CHAR

Full address (street, street number, ZIP, city, country) of the user’s affiliation.

email: (required) NX_CHAR

Email address of the user.

orcid: (recommended) NX_CHAR

Author ID defined by https://orcid.org/.

telephone_number: (recommended) NX_CHAR

Official telephone number of the user.

INSTRUMENT: (required) NXinstrument

General properties of the temperature dependent IV curve measurements equipment

IVvoltage_source: (required) NXsensor

Specify the used voltage source used in the voltage sweep for the IV measurement.

model: (optional) NX_CHAR

Free-text desribing the model and make of the voltage source which is used for the IV sweep measurement.

name: (optional) NX_CHAR

Custom name of the voltage source for the IV sweep given by the user/institution.

measurement: (optional) NX_CHAR

Free-text describing the measurement performed in a few words.

type: (optional) NX_CHAR

Free-text describing the type of voltage setting: an internal sweep using the functionality of the voltage supply, or a set/wait/read/repeat mechanism.

IVcurrent_source: (required) NXsensor

Specify the used current source used in the voltage sweep for the IV measurement.”

model: (optional) NX_CHAR

Free-text desribing the model and make of the current source which is used for the IV sweep measurement.

name: (optional) NX_CHAR

Custom name of the current source for the IV sweep given by the user/institution

measurement: (optional) NX_CHAR

Free-text describing the measurement performed in a few words

type: (optional) NX_CHAR

Free-text describing the type of current measuring: an internal sweep using the functionality of the voltage supply, or a set/wait/read/repeat mechanism.

calibration: (optional) NXsubentry

Calibration of the temperature sensor is possible

calibration_time: (required) NX_DATE_TIME

ISO8601 datum when calibration was last performed before this measurement. UTC offset should be specified.

temperature_control: (optional) NXsubentry

Describes the system for controlling the temperature if temperature control was used.

type: (required) NX_CHAR

What kind of temperature control was used? PID, custom temp control?

temp_sensor_type: (required) NX_CHAR

Specify the temperature sensor that was used

Any of these values: thermocouple | thermistor | RTD | other

other_temp_sensor: (optional) NX_CHAR

If you specified ‘other’ as temperature sensor, please write down what it is.

raw_temp_data: (optional) NX_NUMBER (Rank: 1, Dimensions: [N_raw_temp_data])

Data of the most principal measurement of the temperature. For example resistance of a Pt1000.

conversion_function: (optional) NX_CHAR

Algebraic function that is used to determine temperature from the raw_temp_data. All values should be given in SI units.

PID_settings: (optional) NXenvironment

Specify the settings of the PID temperature controller: K_p, K_i, and K_d values used for the temperature control

K_p_value: (required) NX_NUMBER

Proportional term. The proportional term produces an output value that is proportional to the current error value. The proportional response can be adjusted by multiplying the error by a constant Kp, called the proportional gain constant.

K_i_value: (required) NX_NUMBER

The contribution from the integral term is proportional to both the magnitude of the error and the duration of the error. The integral in a PID controller is the sum of the instantaneous error over time and gives the accumulated offset that should have been corrected previously. The accumulated error is then multiplied by the integral gain (Ki) and added to the controller output.

K_d_value: (required) NX_NUMBER

The derivative of the process error is calculated by determining the slope of the error over time and multiplying this rate of change by the derivative gain K_d. The magnitude of the contribution of the derivative term to the overall control action is termed the derivative gain, K_d

SAMPLE: (required) NXsample

Properties of the sample, its history, the sample environment and experimental conditions (e.g. surrounding medium, temperature, pressure etc.), along with the data (data type, wavelength array, measured data).

sample_name: (required) NX_CHAR

Descriptive name of the sample

sample_history: (required) NX_CHAR

Ideally, a reference to the location or a unique (globally persistent) identifier (e.g.) of e.g. another file which gives as many as possible details of the material, its microstructure. In the case that such a detailed history of the sample is not available, use this field as a free-text description to specify details of the sample and its preparation.

preparation_date: (recommended) NX_DATE_TIME

ISO 8601 date with time zone specified. UTC offset should be specified.

data_identifier: (required) NX_NUMBER {units=NX_UNITLESS}

An identifier to correlate data to the experimental conditions, if several were used in this measurement; typically an index of 0 - N

measured_data: (required) NX_NUMBER (Rank: 3, Dimensions: [N_data_points, N_variables, N_different_temperatures])

Resulting data from the measurement, described by data type.

environment_conditions: (optional) NX_CHAR

Information about external parameters that have influenced the sample.

varied_parameters: (optional) NX_CHAR

Indicates which parameter was changed. Its definition must exist below. The specified variable has to be number_of_runs long, providing the parameters for each data set.

Obligatory value: temperature

plot: (optional) NXdata

A default view of the data. The current (y-axis) should be plotted against the voltage (x-axis) with color coding for the temperature of each IV-curve.

@long_name: (required) NX_CHAR

IV curve.

voltage: (required) NX_NUMBER (Rank: 1, Dimensions: [N_data_points]) {units=NX_VOLTAGE}

Array of voltage values on the independent axis supporting the curve.

current: (required) NX_NUMBER {units=NX_ANY}

Array of current values on the dependent axis of the curve.

Hypertext Anchors

List of hypertext anchors for all groups, fields, attributes, and links defined in this class.

NXDL Source:

https://github.com/FAIRmat-Experimental/nexus_definitions/tree/fairmat/contributed_definitions/NXiv_temp.nxdl.xml