[英]Using Scherrer equation for calculating the grain size
我正在尝试通过Scherrer方程计算晶粒尺寸,但我陷入了FWHM。
import numpy as np
#import math
k = 0.94
wave_length = 1.5406e-10
data = np.genfromtxt("G3.txt")
indice = np.argmax(data[:,1])
peak = (data[indice, :])
#D = (k*wave_length) / (beta*cos((math.radian(theta))
信息: Scherrer方程 , 半 峰 全宽 , 相关问题
这是一个工作示例,假设您具有正态分布。 我在Jupyter控制台中运行它,因此,如果您不这样做,则必须跳过“魔术行”( %matplotlib notebook
),并在最后添加plt.show()
。
%matplotlib notebook
import matplotlib.pyplot as plt
from scipy.optimize import curve_fit
import numpy as np
numb = 500 # data size
fwhm_in = 3 # set FWHM for the artificial data
sigma = fwhm_in/2/np.sqrt(2*np.log(2)) # calculate sigma
xval = np.linspace(-10, 10, numb) # calculate x and y values using the formula from Wikipedia (see link in question)
yval = (sigma*np.sqrt(2*np.pi))**(-1)*np.exp(-(xval)**2/(2*sigma**2))+np.random.normal(0, 0.03, numb)
def fitFunc(x, x0, sigm): # this defines the fit-function
return (sigm*np.sqrt(2*np.pi))**(-1)*np.exp(-(x-x0)**2/(2*sigm**2))
guess = (0.5, 2) # tell the code with which values it should start the iteration. Close but not equal to the real values
fitParams, fitCovariance = curve_fit(fitFunc, xval, yval, guess) # do the actual fit
print(fitParams)
print('FWHM_calc = {:.3f}'.format(fwhm_in))
fwhm_fit = 2*fitParams[1]*np.sqrt(2*np.log(2)) # calculate the FWHM from the fitted sigma ( = fitParams[1], since fitParams[0] is the offset x0)
print('FWHM_fit = {:.3f}'.format(fwhm_fit))
plt.plot(xval,yval, 'r.', label='data')
plt.plot(xval, fitFunc(xval, fitParams[0], fitParams[1]), 'k-', label='fit', linewidth = 3)
plt.grid(True)
plt.legend()
ax = plt.gca()
ax.axvline(fwhm_fit/2, color='b')
ax.axvline(-fwhm_fit/2, color='b')
我不知道如何在python中解决这个问题(至少目前是这样)。 所以我在Matlab中做到了。
clear all
clc
A = dlmread('YOUR DATAS'); %Firstly add to path
plot(A(:,1),A(:,2)) %Plotting the graph
hold on
min_peak = input('Just write a value that is higher than minimum peak values: ');
%This value must be between requested peaks and non-requested peaks (you can see this in graph)
[yval, yval_i] = findpeaks(A(:,2),'MinPeakHeight',min_peak); %Finding peaks
scatter(A(yval_i,1), yval); %Showing peaks
Beta = [];
xval = [];
for k = 1:size(yval_i,1) %Finding x values corresponding to y (peak) values
xval1 = A(yval_i(k),1);
xval = [xval xval1];
end
Theta = xval / 2;
for i = 1:size(yval,1) %Finding half of max. peak values
yval_i1 = yval_i(i,1);
while (yval(i,1))/2 < A(yval_i1+1,2)
yval_i1 = yval_i1+1;
end
yval_i2 = yval_i(i,1);
while (yval(i,1))/2 < A(yval_i2-1,2)
yval_i2 = yval_i2-1;
end
plot(A(yval_i2,1)*ones(size(A(:,2))), A(:,2));
plot(A(yval_i1,1)*ones(size(A(:,2))), A(:,2));
% hold on
% scatter(A(yval_i1,1),A(yval_i1,2))
% scatter(A(yval_i2,1),A(yval_i2,2))
B = abs(A(yval_i1,1)-A(yval_i2,1));
Beta = [Beta B];
end
Beta
K = 0.94;
Lambda = 1.5406e-10;
To = [];
for j = 1:size(Beta,2)
To1 = (K*Lambda)/(Beta(j)*cos(Theta(j)));
To = [To To1];
end
To = abs(To)
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